Radionuclides Transfers in Air, Soils and Watercourses

The presence of radionuclides (radioactive atoms) in the environment exposes human, plant and animal populations to the radiation they emit. These radionuclides are of natural or artificial origin . Artificial radionuclides present in the French environment mainly come from fallout from atmospheric testing of nuclear weapons and from the Chernobyl accident, as well as from radioactive discharges resulting from various human activities, notably those linked to nuclear power generation.

Radioecology studies the transfer of radionuclides in the environment. It draws on a variety of scientific fields, including ecology, which deals with the relationships between organisms and the environment in which they live, with components from the human sciences (notably geography) and agronomy in the broadest sense (including animal husbandry techniques) to better take into account the complex relationships between man and his environment. Elements of biology, physics and geochemistry are also involved in the study of transfer phenomena and mechanisms observed in situ or experimentally. In addition, mathematics is involved in the construction of models that enable knowledge to be synthesized quantitatively and used operationally for predictive purposes, notably for impact studies of nuclear facilities.

Together with radiotoxicology and radiobiology , which respectively study the toxicity of radionuclides on living organisms and the biological effects of radiation, radioecology contributes to radiation protection.

This article deals with the dispersion of radionuclides in the air, their deposition on surfaces, their migration in soils and their dispersion in watercourses. Following a description of the phenomena governing these transfers, modeling examples (equations and parameter values) are presented to give the reader an idea of the intensity of the transfers, and to enable estimates of volumetric, surface or mass activities in the media concerned.

Given the complexity of the phenomena involved in these transfers, and of the most advanced models used to model them, this article presents only the simplest models used in operational radioecology. However, as their...